Method, device and system for adjusting mobility management

ABSTRACT

It is disclosed a method of adjusting mobility management in a mobile communication network, said mobile communication network comprising a mobility control unit ( 4; 40; 320 ) adapted to track location of communication units ( 1; 10; 310 ) communicating in said mobile communication network and to control the mobility management for said communication units. Mobility information related to a communication unit is provided (S 1 ) to said mobility control unit, which evaluates (S 2 ) the degree of mobility of said communication unit from said mobility information related to said communication unit. On the basis of said evaluated degree of mobility, mobility management elements used for mobility management of said communication unit in said mobile communication network are correspondingly adjusted (S 3 ). Furthermore, there are disclosed a corresponding mobility control unit, a corresponding communication unit as well as a corresponding mobility management adjustment system.

FIELD OF THE INVENTION

The present invention relates to a method for adjusting mobilitymanagement (MM) settings in a mobile communication network, e.g. acellular mobile communication network, and in particular to a method foroptimizing the MM settings for a machine to machine (M2M) application ina mobile communication network. The present invention is also related toa corresponding mobility control unit, a communication unit and/or acorresponding system.

BACKGROUND OF THE INVENTION

In the last years mobile communication became more and more popular. Newdevelopments in this field of telecommunication open up an everincreasing number of new application areas.

One of these new application areas is a M2M application. M2M stands formachine-to-machine, mobile-to-machine and/or machine-to-mobilecommunication. The purpose is to enable controlling procedures,monitoring procedures, parameter setting procedures, transactionprocedures and the like with machines such as vending machines,elevators, pumps and meters and the like via a mobile communicationsystem. In other words, communication connections between systems,devices and individuals are to be established. This can be done, forexample, via the Internet with which mobile communication networks canalready establish connections and perform data transmission. As wirelessaccess methods can be used, for example, CSD (Circuit Switched Data),HSCSD (High Speed Circuit Switched Data), GPRS (General Packet RadioService), USSD (Unstructured Supplementary Services Data) and SMS (ShortMessage Service), which are all commonly known to a person skilled inthe art and for which a detailed description is omitted. M2Mapplications can be employed in different types of carrier devices whichare placed on mobile or static platforms, for example static vendingmachines or mobile devices in cars, or the like.

When a wireless connection for a communication unit of the M2Mapplication is used, as for example a mobile communication connection,the M2M communication unit is treated like any other common mobilestation (mobile phone). This means that all procedures to be executed inorder to establish a connection between the M2M communication unit andthe mobile communication network are done as usual, such as callcontrol, mobility management (abbreviated hereinafter as MM), and thelike.

Commonly agreed standards for MM, e.g. in a GPRS environment, aredisclosed, for example in 3GPP (3rd Generation Partnership Project)specifications TS 24.008 V3.9.0 (2001-09) and TS 23.060 V3.9.0(2001-10). In these specifications, among others, in particular MMprocessing and the adjustments of MM timers (ready timer, periodicrouting area (RA) update timer, mobile reachable timer) in mobilestations and network control nodes such as SGSN (serving GPRS supportnode) are described as they are usually to be performed. The termsstandby state, ready state, ready timer, periodic location area update,periodic RA update, location area (LA) update, periodic RA update timer,cell update, mobile reachable timer, which are commonly known by aperson skilled in the art, are for example defined in these referred3GPP specifications TS 24.008 V3.9.0 (2001-09) and TS 23.060 V3.9.0(2001-10). A particular example of MM procedure is how long is an mobilestation maintained in ready mode (2G GPRS) and how often a periodicupdate (e.g. periodic Routing Area (RA) update in GPRS) is performed.

Currently MM timers are optimized based on average behavior of a Mobilestation (MS), i.e. MS mobility (affecting e.g. number of RA update;number of cell updates; probability to move out of coverage) and MStraffic pattern (affecting e.g. probability to be paged). In addition,MM timers takes into account various other factors such as a RA size(affecting e.g. number of RA update and paging load) and quality ofcoverage (affecting e.g. probability to move out of coverage).

For better understanding, a short description of present mobilitymanagement in different mobile communication systems, e.g. in a mobileswitching center (MSC), second generation serving GPRS support node (2GSGSN), 3G SGSN, and relevant differences thereof is given. These,however, are known to persons skilled in the art.

A 2G SGSN tracks the location of an MS at a cell level in ready mode,and in RA level in stand-by mode. The MS and network stay in ready modefor the duration of the ready timer after the last uplink transmission.After that both change to stand-by mode where RA Update are made when RAchange or periodic RA Update timer expires. In order to prevent fastmoving MS to, stay always in ready mode (as they always make cell updatebefore ready timer expiry), the SGSN may force the MS to move tostand-by after a routing area update procedure. The ready timer andperiodic RAU timer values are indicated to the MS in the attach acceptor RA Update accept message.

A 3G SGSN tracks the location of an MS at radio network controller (RNC)level in MM-Connected mode, and in RA level in MM-IDLE mode. RNC tracksthe user at cell or URA (UTRAN (UMTS Terrestrial Radio Access Network)Registration Area) level. The RNC has a mobility management (sometimesreferred as location management) mechanism very similar to the MMmechanism described above as it also has periodic cell or URA updateprocedure. The periodic timer (value) applicable is broadcasted in thearea. The MS and network stay in MM-Connected mode until this one isexplicitly released. A corresponding release request may be initiatedfrom the RNC (e.g. triggered by an inactivity timer or triggered bydetecting the maximum number of URA update without data transmission) orfrom the SGSN (e.g. by moving back the MS to MM-Idle state aftercompletion of a RA update procedure). In the MM-Idle mode, RA updatesare made when the RA changes or when the periodic RA update timerexpires.

The ready timer and periodic RA update timer values are indicated to theMS in the attach accept or RA update accept message for both 2G and 3G.It is to be noted that this ready timer value is sent also in 3Gprotocols (due to the desired interoperability with 2G) although 3G doesnot comprise a ready state.

An MSC (2G or 3G) tracks the location of an MS at RNC or base stationcontroller (BSC) level in MM-Connected mode (i.e. during a call), and inLA level in MM-IDLE mode. The MS and network stay in MM-Connected modeuntil this one is explicitly released. The release request may beinitiated from the RNC (e.g. due to a loss of coverage during the call)or from the MSC (e.g. due to an end of the call). In MM-Idle mode,location updates are made when the LA changes or a periodic LocationUpdate timer expires. The periodic Location Update timer value iscurrently indicated to the MS in the broadcast information (thus, all MSin same location area use the same value).

However, when a large number of additional communication units for M2Mapplications are introduced in the existing mobile communication networkstructures this will result in an increase in the signaling load for thenetworks.

In document WO 00 38469 A an apparatus and a method for providing pagemessages to mobile radios based on the mobility rates of the mobileradio are described. For mobile radios that are relatively stationary,page messages are sent to a cell in which the mobile radio resides,while radios which are increasingly mobile receive their page messageson a local area basis. The mobile radio only performs location updateswhen the situation is optimized for doing so depending upon the mobilityof the radio, the introduction of a new cell, the introduction of a newlocation area, the expiration of a pre-determined time limit and thestatus of a new cell location flag. A function is defined for locationupdating on either a locationary basis or a cell basis in accordancewith each of the above factors in order to optimize the burden oflocation area updating and unwanted page broadcasting.

In document WO 99 52306 A a method in the packet switched datatransmission between a wireless communication device and a packetnetwork is described, in which data transmission between the wirelesscommunication device and the packet network is controlled with at leastone packet switching controller (SGSN). A group of connection states isdefined in the method, from said connection states one is selected at agiven time, and the selected connection state is set to the wirelesscommunication device and to the packet switching controller. Inaddition, said connection states are defined in the method to be: aready state, in which packets are transmissable in an activated datatransmission connection, a standby state, in which data transmissionconnection packets to be transmitted and received are waited for, and anidle state, in which the data transmission connection is deactivated. Asa connection state also an extended ready state is defined, to which atransition from the ready state is conducted, and in which datatransmission connection packets to be transmitted or received are waitedfor.

In “Location management strategies for mobile cellular networks of3^(rd) generation” by D. Plassmann, Vehicular Techn. Conf., 1994, IEEE44^(th) Stockholm, Sweden, 8.10 June 1994, New York, N.Y., USA, IEEE, 8Jun. 1994, pages 649-653, XP010123353 ISBN:0-7803-1927-3, severallocation management strategies applicable in cellular networks aredescribed. Analytical modelling approaches for signalling costminimisation are discussed. Results of a GSM based case study are givenwhich are applicable to cellular radio systems of the 3^(rd) generationlike MBS and UMTS. A hybrid dynamic strategy is proposed for a publicMBS.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved methodof adjusting the mobility management in a mobile communication network,and to provide a corresponding system and/or units which improve themobility management adjustment in the mobile communication network.

This object is achieved, for example, by a method of adjusting mobilitymanagement according to claim 1.

Furthermore, this object is achieved, for example, by a mobility controlunit according to claim 15.

Additionally, this object is achieved, for example, by a communicationunit according to claim 29.

Furthermore this object is achieved, for example, by a mobilitymanagement adjustment system according to claim 34.

Advantageous further developments of the present invention are as setout in the respective dependent claims.

The mobility information related to said communication unit may includea specific information element indicating a periodic update timer valueand/or predefined mobility management parameter for mobility managementelements of said communication unit and/or said mobility control unit,said periodic update timer value and/or predefined mobility managementparameter being detected in said evaluating step.

Furthermore, said mobility information related to said communicationunit may include previous location information and current locationinformation of said communication unit, said previous locationinformation and current location information being compared in saidevaluating step to determine whether they are equal.

In the adjustment, said timer elements (or mobility management elements)of said communication unit and/or said mobility control unit may be setto predefined changed periodic update timer values and/or predefinedchanged mobility management parameters.

Furthermore a function of the mobile communication network, which isused to force a modification of an operation state of the communicationunit, may be disabled during the MM adjustment.

The communication unit may be employed in a static device used for a M2Mapplication, such as a vending machine. This means that thecommunication unit represents an “immobile mobile station”.

The mobility control unit may be integrated in a core network controlunit of the mobile communication network. The present invention can beemployed in different types of mobile communication networks, such ascircuit switched or packet switched networks, 2^(nd) or 3^(rd)Generation communication networks (GSM, UMTS) and the like. Thus, thecore network control unit may be, for example, a mobile switching center(MSC) or a SGSN. However, also other network control elementscontrolling the MM can be employed.

The timer elements (or mobility management elements) may be timerelements of said communication unit and said mobility control unit, e.g.ready timers, periodic routing area update (RAU) timers or periodic LUtimer of said communication unit and/or said mobility control unit (e.g.core network control unit).

The mobility information related to said communication unit may beprovided from said communication unit. Furthermore, the mobilityinformation related to said communication unit may be provided from acore network control unit of the mobile communication network.

The mobility information may include a request for setting at least onetimer element (or mobility management element) to a maximum value or arequest for deactivating at least one mobility management element.Correspondingly, the timer elements (or mobility management elements)may be set to maximum setable values and/or may be deactivated.Alternatively, the timer elements (or mobility management elements) maybe set to values which are incremented by a predetermined amount incomparison to the values set before. By using the present invention itis possible to optimize mobile communication system settings with regardto parameters like location accuracy level, timer threshold values andthe like used for MM. In other words, it is possible to advantageouslydecrease signaling load with regard to the MM processing in mobilecommunication networks in comparison to the generic MM processing. Inparticular in cases in which a M2M communication unit is, for example, astatic device, it is possible to reduce MM signaling significantly bymeans of adjusting, for example, the ready timer and the periodicrouting area update timer of the communication unit as well as the readytimer in the core network control unit to predefined changed values,e.g. to maximum values. The adjustment is preferably initiated by amobility control unit, e.g. integrated in a core network control unit,which is adapted to identify a mobility information related to the M2Mcommunication unit to be controlled. If this specific mobilityinformation element is identified, the improved MM adjustment processingis executed after which periodic updates are made as rarely as possible,and e.g. in a 2G GPRS system, the communication unit is maintained inthe ready state for a long time. When the M2M communication unitmaintained in the ready mode is a static device, no increase ofsignaling load by cell update requests will result. However, a signalingload due to paging (when the communication unit is to be reached) issignificantly reduced. Since the communication unit is held in the readystate for a long time, the need for paging is reduced. Furthermore,since also e.g. the periodic routing area update timer is set to themaximum value and the long duration of the ready timer delays periodicRA update requests, also the signaling load due to periodic RA update isreduced.

Preferred embodiments of the invention are described herein below indetail by way of example with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a part of a mobile communication network for illustrating aMM adjustment procedure,

FIG. 2 is a flow chart illustrating a MM adjustment procedure,

FIG. 3 shows a part of a mobile communication network for illustrating aMM adjustment procedure,

FIG. 4 is a flow chart illustrating a MM adjustment procedure,

FIG. 5 is a diagram illustrating a signaling connection in the mobilecommunication network of FIG. 3,

FIG. 6 is a flow chart illustrating an adaptive MM adjustment procedure,

FIG. 7 is a flow chart illustrating an adaptive MM adjustment procedure,and

FIG. 8 shows a part of a mobile communication network for illustrating aMM adjustment procedure.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, the concept of the MM adjustment isdescribed. According to FIG. 1, a M2M communication unit 1 is (wireless)connected with a mobile communication system 3. Via this wirelessconnection, signaling and traffic data communications are sent andreceived by the M2M communication unit. The control of thiscommunications is placed in respective network elements (not shown) ofthe mobile communication network 3, as commonly known. Furthermore, amobility control unit 4 is provided which is used to execute the MMadjustment. For this purpose, mobility information is received by themobility control unit 4 (step S1 in FIG. 2). This mobility informationare evaluated in the mobility control unit 4 in order to detect a degreeof mobility of the respective M2M communication unit 1 (step S2 in FIG.2). On the basis of this evaluated degree of mobility, the mobilitycontrol unit 4 is adapted to initiate an adjustment of the MM processingin the communication network for the M2M communication unit 1 (step S3in FIG. 2). This will also be described later.

The mobility control unit 4 can be located at different places in themobile communication network. It may be integrated, for example, in acore network control unit executing the MM processing, e.g. in a 2GSGSN, 3G SGSN, MSC and the like (i.e. the respective core networkelement is also the mobility control unit). However, it may be alsoimplemented in a network element outside the core network structure, forexample at a RNC of a 3G mobile communication network.

The mobility information may comprise different contents. For example,specific values for mobility management timers (ready timer, periodic RAupdate timers and the like), an explicit parameter used as an indicationof mobility for the M2M communication unit, information concerning thehistorical behavior of M2M communication unit (no movement within thecoverage area of the cellular mobile communication unit, or the like)can be used by the mobility control unit for the evaluation of thedegree of mobility.

The mobility information can be sent from respective different sourcesin the mobile communication network. One source can be, for example, theM2M communication unit 1 itself, preferably in cases of mobilityinformation contents like a specific value for mobility managementtimers or an explicit parameter used as an indication of mobility.However, it is also possible that the source for the mobilityinformation is another network element, for example a core networkelement as a SGSN, for example in a case of mobility informationcontents like the historical behavior of M2M communication unit.Nevertheless, such historical behavior information contents can beprovided also by the M2M communication unit 1.

The adjustment of the MM by the mobility control in the mobilecommunication network may comprise a change of setting of mobilitymanagement elements of the communication unit 1 and/or of the mobilitycontrol unit 4 (e.g. of a SGSN or the like). The mobility managementelements are, for example, timers (ready timer, periodic RA updatetimer) whose values are changed. It is also possible to increment thesevalues step by step. This means, the mobility management elements(timers) are set to predefined changed values which are for examplestored in the mobility control unit.

Further embodiments and modifications thereof of the MM adjustment aredescribed hereinafter for different applications. For the sake ofsimplicity only parts of the overall mobile communication networks areshown in order to show up the measures to reach the improved MMprocessing.

However, as commonly known, mobile communication networks may compriseseveral other, elements.

FIG. 3 shows a block diagram of a mobile communication network 30 inwhich the improved MM processing is implemented. According to FIG. 3, a2^(nd) generation GPRS communication network is described. However, itis easy to understand that also other mobile communication networks canbe used (3^(rd) generation, CSD, and the like).

In FIG. 3, reference sign 10 denotes M2M communication units. A M2Mcommunication unit 10 represents preferably a static device such as avending machine or the like. The M2M communication unit 10 is adapted tocommunicate with the mobile communication network, for example via apacket switched GPRS communication connection, in order to exchange data(control and/or traffic data).

Reference sign 20 denotes a base station subsystem of the mobilecommunication network. The base station subsystem 20 is connected withthe communication units 10, for example, via air interfaces (shown bydotted lines). The base station subsystem 20 is adapted to establish aconnection between the communication units 10 and the remaining mobilecommunication network elements by forwarding signaling and traffic datathrough corresponding channels or connections to and from thecommunication units 10.

Reference sign 40 denotes a SGSN as a core network control unit. Thecore network control unit is adapted to control the elements of themobile communication network and to perform control procedures forcommunication connections in the mobile communication network. Inparticular, the core network control unit is adapted to execute the callcontrol (MSC) or Session Management (SGSN) and MM procedures for thecommunication units 10 connected to the mobile communication network 30.This means that the core network control unit 40 determines parametersused for the MM such as timer values and initiates the settings or theadjustment thereof. Moreover, the core network control unit is adaptedto establish connections to other networks, e.g. via gateways (notshown), and to other communication units connected to the mobilecommunication network, e.g. via base station subsystems. According tothis embodiment, the SGSN 40 is provided with a mobility control unitadapted to execute a MM adjustment.

As shown in FIG. 4, MM timers are connected with the M2M communicationunit 10 and the SGSN 40. Ready timers 15, 45 define the time period inwhich the M2M communication unit remains in the ready state. A periodicRA update timer 16 is used to control a procedure in the M2Mcommunication unit 10 to periodically notify the availability of the M2Mcommunication unit 10 to the mobile communication network. This means,the periodic RA update timer 16 is used to detect when an MS losecoverage. A mobile reachable timer 46 is used to monitor the periodic RAupdate procedure in the SGSN.

With reference to FIGS. 4 and 5, the improved MM procedure beingperformed in the MM adjustment in the mobile communication networkdescribed above is illustrated.

In the MM adjustment procedure according to the embodiment, first, theM2M communication unit 10, for example a vending machine, sends aregistration message via the base station system 20 to a SGSN 40representing the core network control unit of the mobile communicationnetwork 30 (step S20 in FIG. 4; message M1 in FIG. 5). Usableregistration messages are, for example, an attach request or a RA updaterequest from said M2M communication unit 10. Said registration messageM1 further comprises a specific mobility information element adapted toindicate the degree of mobility (or immobility) of the requesting M2Mcommunication unit 10. In other words, said specific mobilityinformation is used to indicate the core network, at least implicitly,that the M2M communication unit is likely not to move within the area ofthe mobile communication network. Hence, it indicates that, e.g., a RAupdate procedure will probably not occur. According to a first example,said specific information element is a request to set MM timer(s) (e.g.ready timer 15, 45, and periodic RA update timer 16) to a specificvalue, namely to the maximum setable value. It is proposed to use for 2Gand 3G GPRS, the requested READY timer value. In the case of presentlyused mobile communication networks this value may be a little time overthree hours.

The SGSN 40 receives the registration request M1 comprising the specificmobility information and identifies the specific mobility information asan indication of the degree of mobility of the requesting M2Mcommunication unit 10 (step S30 in FIG. 5). For this purpose, the SGSN40 may comprise a specific device (not shown), e.g. a softwarecomponent, which is adapted to perform the identification and toinitiate the improved MM processing. This is preferably performed in themobility control unit, e.g. by using a pre-stored value for acomparison, or the like.

In the identification process (step S40 in FIG. 4), the SGSN 40determines whether the specific mobility information comprises anacceptable value indicating the immobility of the M2M communication unit10, e.g. the request for the maximum value of the MM timers. If thisacceptable value is not recognized, i.e. when no indication ofimmobility can be recognized, a generic MM processing with normal timeradjustment may be performed (step S50 in FIG. 4). It is to be noted thatinteroperability is maintained with node not implementing thisidentification process, as they will always use normal timer adjustment.

Otherwise, when the SGSN 40 determines in step S40 that the specificinformation element comprises an acceptable value, i.e. it identifiesthe immobility of the requesting M2M communication unit 10, another MMprocessing will be performed. In this case, predefined changed valuesfor the MM timers will be determined (step S60 in FIG. 4) by the SGSN40, for example by means of the mobility control unit, on the basis ofthe specific information element. For example, the specific mobilityinformation itself may be used as the value for the MM timer settingwhen the specific information element comprises the maximum value forthe MM timers (e.g. the maximum value of the ready timers 15, 45). Alsoa table or the like stored in the SGSN 40 can be used in which thevalues for the MM timers related to the specific mobility informationare stored. Additionally, also values for MM timers other than the readytimers 15, 45, e.g. the periodic RA update timer 16, are determined tobecome maximum values (in case of recently used mobile communicationunits, the maximum value for periodic RA update timer may be some timeover three hours).

When the ready timers 15, 45 and the periodic RA update timer 16 are tobe adjusted to the maximum values, according to the predefined changedvalues determined in step S60, the SGSN 40 adjust the ready timer 45connected with the SGSN 40 to the determined maximum value. Furthermore,the SGSN 40 transmits the determined MM timer setting values to therequesting M2M communication unit 10 in connection with an acceptancemessage M2 (FIG. 5) for the registration request M1 (step S70 in FIG.4), i.e. an attach accept message or a RA update accept message. Thedetermined MM timer setting values in the message M2 comprises themaximum values for the ready timer 15 and the periodic RA update timer16. These maximum values are used by the M2M communication unit 10 toadjust the MM timers in the M2M communication unit 10 such that themaximum time period is achieved for both MM timers (step S80 in FIG. 4).In parallel, the SGSN 40 has adjusted its MM timer(s) (i.e. the readytimer 45 and its mobile reachable timer 46) to the maximum value,wherein in practice a small time delay is to be considered due to thetransmission time required so as to ensure that both ready timers 15, 45match. Thereafter, the MM processing is ended (step S90 in FIG. 4).

Preferably, the SGSN 40 is controlled in such way that a “Forced tostandby” procedure, which is usually performed in the generic MMprocessing to force a mobile station to enter from the ready mode into astandby mode, is not performed in answering periodic RA update from sucha M2M communication unit 10. For this purpose, for example, anindication that the M2M communication unit 10 is immobile is stored in amemory (not shown) to which the SGSN 40 refers to when a “Forced tostandby” processing is to be executed. This storing may be performed forexample in connection with step S70. When this indication for therespective M2M communication unit can be found in said memory, the“Forced to standby” processing will be disabled.

Preferred values for the setting of the ready timer and the periodic RAupdate timer are presently, for example, a little bit over 3 hours,respectively. Thus, the overall time (i.e. time of ready timer+time ofperiodic RA update timer) is somewhat over 6 hours. Hence, routing areaupdate is performed as rarely as possible, which is to be preferred asthe M2M communication unit is not moving. Hence, MM signaling load canbe reduced by the improved MM adjustment in comparison to generic MMprocedure. For example, in comparison to the generic MM in which for acommunication unit (also for a static one) the ready timer is set to 36seconds and periodic RA update timer is set to 3 hours, the loadgenerated by the static M2M communication unit adjusted with the valuesas described is divided by 2. For a M2M communication unit for which theready timer is set to 36 seconds and periodic RA update timer is set to30 minutes, the load generated is divided even by 12.

Additionally, the paging load is reduced in the mobile communicationnetwork as the communication unit 10 remains a long time in the readystate, due to the high value for the ready timer, and the SGSN 40 isaware of that fact.

Alternatively to the above described embodiment, it is also possiblethat the M2M communication unit 10 requests, instead a specific valuefor the ready timer, a value indicating a deactivation of the readytimer.

In such case there are at least two possible ways for the SGSN 40 toreact. Which one of these is to be selected may depend, for example, onoperator's presettings of the SGSN 40.

First possibility is that the SGSN 40 accepts this value, i.e. thedeactivation of the ready timer. A corresponding setting for the MMtimers will then be transmitted to the M2M communication unit 10(equivalent to step S70 in FIG. 4) which is processed by the M2Mcommunication unit 10 to deactivate the ready timer 16. A correspondingprocessing is performed by the SGSN 40 with regard to the ready timer45.

This means, that the SGSN stores the requesting M2M communication unitto be always in the ready mode. A possible loss of coverage (e.g. byphysical destruction or battery expiration) will not be detected by thecellular mobile system. However, routing RA update signaling iscompletely suppressed, i.e. the MM signaling load is further reduced.

The second possibility is that the SGSN does not accept this value as itwould suspend mobile reachable timer 46 which is the only way to detectthat an M2M communication unit is not present anymore. In this case, theSGSN 40 (or the mobility management adjustment device comprised therein)may proceed as described in the first embodiment, i.e. adjusting the MMtimers to the maximum value (steps S40, S60 to S90 of FIG. 4).

It should be noted that a benefit of this previous embodiment is thatthis MM adjustment can be existing with the requested READY timer valuewhich are already part of the protocol for 2G and 3G GPRS (see, e.g.,3GPP 24.008). It is to be noted that this ready timer may be sent alsoin 3G protocols (due to interoperability with 2G even is 3G does nothave a ready state), and so this timer (value) may also be used toindicate the degree of mobility in a 3G system.

A second embodiment is that the MS (i.e. the M2M communication unit)reports its mobility to the network (i.e. to the mobility control unit)with a new explicit parameter. The following description is applicableto mobile connected to a MSC. However, the same ideas apply also toother system such as GPRS.

A first option is to indicate the mobility through an explicit mobilitymanagement parameter “mobility indication”. A first simple solution isto indicate only 2 values (static or normal) for this parameter. Thisvalue is then configured in the MS and detected in the mobility controlunit. A second alternative is that this parameter contain a more complexmobility value (e.g. on a scale from 1 to 10, 1 being static, and 10fast moving). This value is derived in a standard way by the MS. Forexample, the MS use the number of cell changes in the last hours (up toa few days). Preferably exponential weight should be applied to givemore weight to recent cell changes than to old one. And the resultingvalue should be mapped to the proposed scale. It should be noted that MSis always aware of cell changes as it has to select on which cell tocamp. This mobility indication is included as a new optional informationelement in the location updating request (used also to attach to theMSC). In the location updating accept message, the MSC includes a newparameter “periodic Location Update timer value”. If the MS receivesthis parameter, it shall use this value instead of the value broadcaston the system information. This kind of MM adjustment requires changesto specifications, but such a mechanism can be introduced withoutbackward compatibility problems. Only MS (e.g. M2M communication units)supporting this feature may send in the request the new parameter“mobility indication”, so only MS supporting this feature may receive inresponse the new parameter “periodic Location Update timer value”. Ifthe MS support this feature, but not the MSC, the MSC will ignore thisunknown optional parameter (“mobility indication”), and so it will notreturn any “periodic Location Update timer value”. The MS will then usethe normal value as broadcast on system information.

A third embodiment is an “adaptive Mobility Management” which isdescribed also with reference to FIGS. 6 and 7. According to thisembodiment, a core network node with a mobility control unit adapted toexecute such an “adaptive MM” is used in the mobile communicationnetwork. The concept of adaptive mobility management is that the corenetwork (e.g. by means of the mobility control unit) monitors the degreeof mobility of the MS without support of the MS (i.e. without anindication from the MS), and adapt its MM behavior (especially MMelements such as MM timers) based on the detected degree of mobility.This third preferred implementation is described in more details for a2G SGSN used by GPRS system connected to a GSM radio network (such asshown in FIG. 3). The 2G SGSN comprises a default periodic RA updatetimer value which is indicated to the MS after an attach or anon-periodic RA update. This means, as shown in FIG. 6, when a RA updaterequest is received by the SGSN, it is checked whether this is aperiodic RA update (steps S100, S110). When the RA update is identifiedto be not a periodic RA update, generic MM timer settings (i.e. forexample default periodic RA update timer value) is used for the MMadjustment (step S120). However when a periodic RA update is identified,step S130 is executed. This means, after a periodic RA update(indicating that the MS did not change RA during the time of theprevious periodic RA update procedure), the new periodic RA Update timeris equal to the old one (as indicated in the periodic RA update request)increased by e.g. 10%. With this solution, a static MS (e.g. M2M device)will quickly (in a few days) reach its maximum periodic RA update timervalue, minimizing the number of RA update load to the system.

Similarly, as for example shown in FIG. 7, in this “adaptive MM”, theready timer is negotiated during the RA update and attach procedure. Itis proposed that the 2G SGSN implements a “change of cell” flag, whichwill be set to TRUE if the cell (i.e the location of the MS) is changingbetween RA update procedures. This requires the SGSN to always store thelast known cell ID (even in Stand-by state) to be able to compare thenew cell with the last known one. After a RA Update procedure iscompleted the flag is set to FALSE. The proposal is that before sendingthe RA Update accept, the SGSN checks the value of this flag. If thisvalue is still false, it means that the MS has not changed cell sincethe previous RA Update, and then the new ready timer indicated to the MSis the old one increased by e.g. 10%. If the value is set to TRUE, thenormal ready timer value (same than after first attach) is returned. Indetail, as depicted in FIG. 7, in step S150 it is checked in the SGSNwhether there is a cell change. If NO, step S170, the “change of cell”flag is set to false. If YES, step S160, the “change of cell” flag isset to true. When a RA update procedure (e.g. periodic RA update) isexecuted (step S180) the SGSN checks whether the “change of cell” flagis set to false (steps S190, S195). (It is clear that similarly also acheck whether the flag is set to be true may be performed). When theflag is not false (i.e. true), the default ready timer value is used forthe MM adjustment (step S220). If the flag is false, in step S200, theindicated ready timer value is incremented (e.g. by 10%), and theincremented ready timer value is used for the MM adjustment (step S210).When the RA update procedure is completed (step S230), the “change ofcell” flag in the SGSN is reset to be false (step S240). Then, theprocess is repeated.

With this solution, a static MS (e.g. M2M device) will quickly (a fewdays) reach its maximum ready timer value, minimizing the number ofpaging and RA Update load (because periodic RA Update timer is startedonly after expiry of the ready timer) in the system.

It should be noted that according to the third embodiment, the timervalues themselves (as normally indicated) are used as an indication ofthe MS mobility. It would be possible to also use a separate indicatoras described above. When the ready timer reaches a high enough value(e.g. one hour), this may be considered as an indication that the MS isvery static. Therefore 2G SGSN should disable the forced to stand-bymechanism based on this indication.

A fourth embodiment is shown, for example, in FIG. 8. According to thefourth embodiment, an implementation of the MM adjustment in a 3G mobilecommunication system 330 comprising, among others, a MS (M2Mcommunication unit) 310, a RNC 320, in which a mobility control unit isintegrated, and core network elements including a SGSN 340 is shown. TheRNC 320 (with the mobility control unit) is adapted to modify theperiodic (cell or URA) update timer value based on an indication of thedegree of the mobility of a MS, i.e. of a M2M communication unit 310.This indication may be sent by the MS 310 in a RRC (radio resourcecontrol) message (similar to the mobility indication in the secondembodiment), it may be derived from past history (similar to theadaptive solution of the third embodiment) or it may be indicated by theSGSN 340 through the insertion of a mobility indication parameter inRANAP (radio access network application part) messages (e.g. commonidentity procedure which is always performed for new Iu connection couldbe used). In case of, e.g., a Serving RNC relocation, a mobilityindication parameter is sent to the Target RNC preferably inside theSource RNC To Target RNC Transparent Container.

According to the fourth embodiment, the value of the periodic updatetimer value is added into the cell update confirm and URA Update confirmRRC message as an optional mobility information element. A MS receivingthis periodic update timer value uses this timer value instead of theone normally broadcast in common system information. Then RNC 320 sets along timer for static MS. The RNC may also adapt the release of the RRCconnection to the mobility of the MS.

As described above, there is disclosed a method of adjusting mobilitymanagement in a mobile communication network, said mobile communicationnetwork comprising a mobility control unit 4; 40; 320 adapted to tracklocation of communication units 1; 10; 310 communicating in said mobilecommunication network and to control the mobility management for saidcommunication units. Mobility information related to a communicationunit is provided (S1) to said mobility control unit, which evaluates(S2) the degree of mobility of said communication unit from saidmobility information related to said communication unit. On the basis ofsaid evaluated degree of mobility, mobility management elements used formobility management of said communication unit in said mobilecommunication network are correspondingly adjusted (S3). Furthermore,there are disclosed a corresponding mobility control unit, acorresponding communication unit as well as a corresponding mobilitymanagement adjustment system.

While preferred embodiments and modifications thereof have beendescribed above, it is also possible to use combinations of theembodiments in a further application. Also, the embodiments and themeasures disclosed therein are not limited to be used in connection withthe respective described network environment (2G, 3G), but can be easilymodified in such that they are compatible with other network structuresas those described in the embodiments.

It should be understood that the above description and accompanyingfigures are merely intended to illustrate the present invention by wayof example only. The preferred embodiments of the present invention maythus vary within the scope of the attached claims.

1-52. (canceled)
 53. Method of adjusting mobility management in a mobilecommunication network, said mobile communication network comprising amobility control unit adapted to track location of communication unitscommunicating in said mobile communication network and to control themobility management for said communication units, said method comprisingthe steps of providing said mobility control unit with mobilityinformation related to a communication unit, evaluating the degree ofmobility of said communication unit from said mobility informationrelated to said communication unit, and, when said step of evaluatingindicates the immobility of said communication unit, adjusting, by saidmobility control unit, values of timer elements of said communicationunit and said mobility control unit to a maximum timer value or a timervalue being higher than a default timer value of said mobilecommunication network, said timer elements defining a time period of aready state of said communication unit and/or a time period forperforming a location update for said communication unit.
 54. Methodaccording to claim 53, wherein said mobility information related to saidcommunication unit includes a specific information element indicating aperiodic update timer value and/or predefined mobility managementparameter for mobility management elements of said communication unitand/or said mobility control unit, said periodic update timer valueand/or predefined mobility management parameter being detected in saidevaluating step.
 55. Method according to claim 53, wherein said mobilityinformation related to said communication unit includes previouslocation information and current location information of saidcommunication unit, said previous location information and currentlocation information being compared in said evaluating step to determinewhether they are equal.
 56. Method according to claim 53, wherein saidadjusting step comprises a step (S80) of setting said timer elements ofsaid communication unit and/or said mobility control unit to predefinedchanged periodic update timer values and/or predefined changed mobilitymanagement parameters.
 57. Method according to claim 53, furthercomprising a step of disabling a function of the mobile communicationnetwork which is used to force a modification of an operation state ofthe communication unit.
 58. Method according to claim 53, wherein saidcommunication unit is employed in a static device used for a M2Mapplication.
 59. Method according to claim 53, wherein said mobilitycontrol unit is included in a core network control unit of the mobilecommunication network.
 60. Method according to claim 53, wherein saidmobility information related to said communication unit is provided fromsaid communication unit.
 61. Method according to claim 53, wherein saidmobility information related to said communication unit is provided froma core network control unit of the mobile communication network. 62.Method according to claim 60, wherein said mobility information includesa request for setting at least one timer element to a maximum value. 63.Method according to claim 60, wherein said mobility information includesa request for deactivating at least one timer element.
 64. Methodaccording to claim 53, wherein in said adjusting step the timer elementsare set to maximum setable values.
 65. Method according to claim 53,wherein in said adjusting step the timer elements are deactivated. 66.Method according to claim 53, wherein in said adjusting step the timerelements are set to values which are incremented by a predeterminedamount in comparison to the values set before.
 67. Mobility control unitin a mobile communication network, said mobility control unit beingadapted to track location of communication units communicating in saidmobile communication network and to control the mobility management forsaid communication units, said mobility control unit comprising meansadapted to receive mobility information related to a communication unit,means adapted to evaluate the degree of mobility of said communicationunit from said mobility information related to said communication unit,and means adapted to adjust, when said means adapted to evaluateindicates the immobility of said communication unit, values of timerelements of said communication unit and said mobility control unit to amaximum timer value or a timer value being higher than a default timervalue of said mobile communication network, said timer elements defininga time period of a ready state of said communication unit and/or a timeperiod for performing a location update for said communication unit. 68.Mobility control unit according to claim 67, wherein said receivedmobility information related to said communication unit includes aspecific information element indicating a periodic update timer valueand/or predefined mobility management parameter for mobility managementelements of said communication unit and/or said mobility control unit,wherein said means adapted to evaluate the degree of mobility of saidcommunication unit detects said periodic update timer value and/orpredefined mobility management parameter.
 69. Mobility control unitaccording to claim 67, wherein said received mobility informationrelated to said communication unit includes previous locationinformation and current location information of said communication unit,wherein said means adapted to evaluate the degree of mobility of saidcommunication unit compares said previous location information andcurrent location information to determine whether they are equal. 70.Mobility control unit according to claim 67, wherein said means adaptedto adjust said timer elements sets said timer elements of saidcommunication unit and/or said mobility control unit to predefinedchanged periodic update timer values and/or predefined changed mobilitymanagement parameters.
 71. Mobility control unit according to claim 67,wherein said mobility control unit is further adapted to disable afunction of the mobile communication network which is used to force amodification of an operation state of the communication unit. 72.Mobility control unit according to claim 67, wherein said communicationunit is employed in a static device used for a M2M application. 73.Mobility control unit according to claim 67, wherein said mobilitycontrol unit is included in a core network control unit of the mobilecommunication network.
 74. Mobility control unit according to claim 67,wherein said mobility information related to said communication unit isreceived from said communication unit.
 75. Mobility control unitaccording to claim 67, wherein said mobility information related to saidcommunication unit is provided from a core network control unit of themobile communication network.
 76. Mobility control unit according toclaim 74, wherein said mobility information includes a request forsetting at least one timer element to a maximum value.
 77. Mobilitycontrol unit according to claim 74, wherein said mobility informationincludes a request for deactivating at least one timer element. 78.Mobility control unit according to claim 67, wherein said means adaptedto adjust the timer elements sets the timer elements to maximum setablevalues.
 79. Mobility control unit according to claim 67, wherein saidmeans adapted to adjust the timer elements deactivates the timerelements.
 80. Mobility control unit according to claim 67, wherein saidmeans adapted to adjust the timer elements sets the timer elements tovalues which are incremented by a predetermined amount in comparison tothe values set before.
 81. Communication unit used in connection with amobile communication network, said mobile communication networkcomprising a mobility control unit adapted to track location ofcommunication units communicating in said mobile communication networkand to control the mobility management for said communication units,said communication unit is adapted to send mobility information relatedto said communication unit, said mobility information being usable bysaid mobility control unit to evaluate the degree of mobility of saidcommunication unit, and to set values of timer elements of saidcommunication unit to a maximum timer value or a timer value beinghigher than a default timer value of said mobile communication network,said timer elements defining a time period of a ready state of saidcommunication unit and/or a time period for performing a location updatefor said communication unit, on the basis of predefined changed periodicupdate timer values and/or predefined changed mobility managementparameters received from said mobility control unit in response to thesending of said mobility information.
 82. Communication unit accordingto claim 81, wherein said mobility information related to saidcommunication unit includes a specific information element indicating aperiodic update timer value and/or predefined mobility managementparameter for mobility management elements of said communication unitand/or said mobility control unit.
 83. Communication unit according toclaim 81, said communication unit is employed in a static device usedfor a M2M application.
 84. Communication unit according to claim 81,wherein said mobility information includes a request for setting atleast one timer element to a maximum value.
 85. Communication unitaccording to claim 81, wherein said mobility information includes arequest for deactivating at least one timer element.
 86. Mobilitymanagement adjustment system used in a mobile communication network,said mobility management adjustment system comprises: a communicationunit; and a mobility control unit, said mobility control unit beingadapted to track location of communication units communicating in saidmobile communication network and to control the mobility management forsaid communication units, said mobility control unit comprising meansadapted to receive mobility information related to a communication unit,means adapted to evaluate the degree of mobility of said communicationunit from said mobility information related to said communication unit,and means adapted to adjust, when said means adapted to evaluateindicates the immobility of said communication unit, values of timerelements of said communication unit and said mobility control unit to amaximum timer value or a timer value being higher than a default timervalue of said mobile communication network, said timer elements defininga time period of a ready state of said communication unit and/or a timeperiod for performing a location update for said communication unit. 87.Mobility management adjustment system according to claim 86, whereinsaid received mobility information related to said communication unitincludes a specific information element indicating a periodic updatetimer value and/or predefined mobility management parameter for mobilitymanagement elements of said communication unit and/or said mobilitycontrol unit, wherein said means adapted to evaluate the degree ofmobility of said communication unit detects said periodic update timervalue and/or predefined mobility management parameter.
 88. Mobilitymanagement adjustment system according to claim 86, wherein saidreceived mobility information related to said communication unitincludes previous location information and current location informationof said communication unit, wherein said means adapted to evaluate thedegree of mobility of said communication unit compares said previouslocation information and current location information to determinewhether they are equal.
 89. Mobility management adjustment systemaccording to claim 86, wherein said means adapted to adjust said timerelements sets said timer elements of said communication unit and/or saidmobility control unit to predefined changed periodic update timer valuesand/or predefined changed mobility management parameters.
 90. Mobilitymanagement adjustment system according to claim 86, wherein saidmobility control unit is further adapted to disable a function of themobile communication network which is used to force a modification of anoperation state of the communication unit.
 91. Mobility managementadjustment system according to claim 86, wherein said communication unitis employed in a static device used for a M2M application.
 92. Mobilitymanagement adjustment system according to claim 86, wherein saidmobility control unit is included in a core network control unit of themobile communication network.
 93. Mobility management adjustment systemaccording to claim 86, wherein said mobility information related to saidcommunication unit is received from said communication unit. 94.Mobility management adjustment system according to claim 86, whereinsaid mobility information related to said communication unit is providedfrom a core network control unit of the mobile communication network.95. Mobility management adjustment system according to claim 93, whereinsaid mobility information includes a request for setting at least onetimer element to a maximum value.
 96. Mobility management adjustmentsystem according to claim 93, wherein said mobility information includesa request for deactivating at least one timer element.
 97. Mobilitymanagement adjustment system according to claim 86, wherein said meansadapted to adjust the timer elements sets the timer elements to maximumsetable values.
 98. Mobility management adjustment system according toclaim 86, wherein said means adapted to adjust the timer elementsdeactivates the timer elements.
 99. Mobility control unit according toclaim 86, wherein said means adapted to adjust the timer elements setsthe timer elements to values which are incremented by a predeterminedamount in comparison to the values set before.
 100. Mobility managementadjustment system according to claim 86, wherein said communication unitis adapted to send mobility information related to said communicationunit, said mobility information being usable by said mobility controlunit to evaluate the degree of mobility of said communication unit, andto set values of timer elements of said communication unit to a maximumtimer value or a timer value being higher than a default timer value ofsaid mobile communication network, said timer elements defining a timeperiod of a ready state of said communication unit and/or a time periodfor performing a location update for said communication unit, on thebasis of predefined changed periodic update timer values and/orpredefined changed mobility management parameters received from saidmobility control unit in response to the sending of said mobilityinformation.
 101. Mobility management adjustment system according toclaim 100, wherein said mobility information related to saidcommunication unit includes a specific information element indicating aperiodic update timer value and/or predefined mobility managementparameter for mobility management elements of said communication unitand/or said mobility control unit.
 102. Mobility management adjustmentsystem according to claim 100, said communication unit is employed in astatic device used for a M2M application.
 103. Mobility managementadjustment system according to claim 100, wherein said mobilityinformation includes a request for setting at least one timer element toa maximum value.
 104. Mobility management adjustment system according toclaim 100, wherein said mobility information includes a request fordeactivating at least one timer element.